The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
Image processing or manipulation is growing in popularity. With the increased power and decrease cost of computers, home users would like to manipulate images for scrapbooks and the like. Likewise, professional editing studios have a need to manipulate images for a wide variety of commercial needs such as advertising and marketing.
One particular need is to have the ability to separate the foreground object(s) (hereinafter referred to as “foreground object” or “foreground”) from the background object(s) (hereinafter referred to as “background object” or “background”) of an image. In this manner for example, the foreground object can be removed from the original image and transferred to a second image, thus making it appear that the second image was taken with the foreground object extracted from the first image.
In order to separate the foreground object from the background, a matte is typically required. The most common approach for obtaining a matte is blue screen matting, in which a foreground object is captured in front of a known solid-colored background, usually blue or green. Blue screen matting is the standard technique employed in the movie and TV industries because a known background greatly simplifies the matting problem. However, blue screen matting requires an expensive well-controlled studio environment to reduce artifacts such as blue spill, backing shadows, and backing impurities. Such a system is not available to the typical consumer. In addition, blue screen matting is less suitable for outdoor scenes.
Other techniques include using a single natural image to obtain the matte. First, the input image is manually partitioned into three regions by the user: definitely foreground, definitely background, and unknown regions. These three regions are collectively referred to as the “trimap”. Then, the matte, foreground color, and background color are estimated for all pixels in the unknown region.
Although these methods and others have produced results, accurately separating the foreground object from the background object is difficult. This is particularly true when the foreground and the background are alike, or when highly textured foreground or background objects are present in the image, for example, the windblown hair of a person taken against a complex background.